N900 consumes too much power

Dne 5.8.2012 21:45, Jan Knutar napsal(a):
> On Sunday 05 August 2012, Pavel Řezníček wrote:
>
>> I am connected all the time to WiFi at home. But even outdoors when
>> not connected, my battery discharges in a couple of hours.
> Are you connected to 3g instead when outdoors? Do you have "switch to
> WLAN when available" enabled?

Hello Jan, thank you for your response and question.
No, I'm usually not connected to 3G when outdoors. I use 3G on merely
rare occasions because it costs money in contrast to WiFi :-)
Actually, I don't have “switch to wlan when available” enabled /but/ cca
98% of all the time I am speaking of I had it enabled.
As I connect rarely to GPRS, 2.5G & 3G cellular data networks and I am
perfectly aware of disconnecting it and switching to WiFi, this is not
my issue.
Anyways, thanks for the tip :-)

Dne 5.8.2012 21:45, Jan Knutar napsal(a):
> On Sunday 05 August 2012, Michael Rösch wrote:
>
>> The biggest leap in saving enery is to use smart-reflex.
> Considering how abnormal his battery use is, I don't think smartreflex is
> the answer. Considering smartreflex only makes a difference when the CPU
> is on, and on a properly configured device, the CPU spends most of the
> time off.
Humm, thanks for this tip, Jan.

My Maemo and N900 knowledge is maybe abnormal (abnormally poor). I
neearly sure not to have a properly configured device. Now it comes the
special moment when I begin to study how to get my N900 properly
configured :-)
For the whole conference: Please be patient with me. I'll report my
steps and results. I hope others will learn something useful from my
case and your suggestions.

Dne 6.8.2012 06:08, rixed@happyleptic.org napsal(a):
> -[ Sun, Aug 05, 2012 at 08:20:17PM +0200, Pavel ??ezní??ek ]----
>> I am connected all the time to WiFi at home. But even outdoors when not
>> connected, my battery discharges in a couple of hours.
> You should try setting the N900 in flight mode (or offline mode,
> whatever it's called) so you can make certain your's not using
> wifi nor 3g nor anything. Then see how long your phone lasts.
>
> Also, while doing so, open a terminal and run "top" for a minute or two
> to check CPU usage by programs. Top itself and Xorg should be on top,
> with only a few % of CPU.
>
Thank you, Rixed.
I'll try the second suggestion.
The first really kicked me! I've never used the offline mode because I
want people to reach me on my phone number.
So I wasn't really right I don't use GPRS/2.5G/3G. I am connected to my
cell operator all the time even when not connected to their data
services! I just only use the call and SMS services.
To be clear: Is it normal to be connected to this basic services all the
time with an N900 device?
Or did you, Rixed, recommend me to go offline only for testing purposes?
To test if the battery lives longer?

A progress anouncement for everybody: I've installed the CSSU! I plan to
watch the battery life in the next days.

Paul Hartman

2012-08-06 15:04 UTC

On Sun, Aug 5, 2012 at 3:52 AM, Pavel Řezníček <cigydd@gmail.com> wrote:
> Dear comaemoers,
>
> I have recently read an article, a review of Nokia N900. The reviewer stated
> that his device lasts 3 days on battery when only sometimes calling or
> writing SMS.
> This is what I hardly can believe because my N900 lasts only 3, max. 6 hours
> on battery and then the battery gets discharged.
> Was the reviewer kidding or is something wrong with my mobile computer?
> I have recently bought a new battery and the effect is minimal.
> My device was in repair service already and they changed the motherboard. It
> helped a bit but I never made it to that 3 days on battery.
> Any ideas? :-)

Using Scud battery + CSSU + kernel-power with smartreflex enabled,
usually but not always connected to either 3.5G cellular internet or
wifi, with email refresh every 15 minutes, no IM or voip accounts, no
wifi autoconnect, brightness set to 2nd lowest setting, usually it
will last me about a day and a half.

If I'm listening to streaming music then battery dies much faster, a
time measured in hours not in days.

Some installed programs/widgets may be consuming CPU, daemons running
in the background. HAM auto-update check can be a killer if you have a
lot of repos enabled. If you are familiar with standard linux tools
you can look in top and similar and find out what's running.

BatteryGraph package is great, it will show when your battery usage is
occurring, whether you are connected to gprs or wifi at the time.
Maybe you can figure out if battery loss is constant or if there's a
particular activity you did that is causing rapid drain.

I also find that battery drain is affected by environmental
conditions. If the N900 is in my pocket all day, or I'm in a place
with poor signal, battery drains faster than if it is sitting on my
desk with full bars.

Cedric Cellier

2012-08-07 01:20 UTC

----- Message d'origine -----
> The first really kicked me! I've never used the offline mode because I
> want people to reach me on my phone number.
> So I wasn't really right I don't use GPRS/2.5G/3G. I am connected to my
> cell operator all the time even when not connected to their data
> services! I just only use the call and SMS services.
> To be clear: Is it normal to be connected to this basic services all the
> time with an N900 device?
> Or did you, Rixed, recommend me to go offline only for testing purposes?

Of course offline mode is not normal. I suggested it
for testing :) So that whatever software is the culprit it can no longer drain the battery very fast. If you can't stand several days in offline mode and without top reporting a process that's heavy on the cpu then you'll be certain your harware is faulty.

Am 05.08.2012 21:45, schrieb Jan Knutar:
> On Sunday 05 August 2012, Michael Rösch wrote:
>
>> The biggest leap in saving enery is to use smart-reflex.
>
> Considering how abnormal his battery use is, I don't think smartreflex is
> the answer. Considering smartreflex only makes a difference when the CPU
> is on, and on a properly configured device, the CPU spends most of the
> time off.

You're right! Of course he has to find that process(es) that drains the
battery.
All information is on the pages that are linked somewhere in the thread.
He statet that he is always connected to wifi at home, well that is the
first thing to stop using Autodisconnect for example.

> Now I don't exactly know what smart-reflex is for now. I surely can
> search for it but if you could explain it also for the others, I'd be
> happy :-)

You can look it up here: http://wiki.maemo.org/Smartreflex

> OK, I'm not sure if I have the kernel-power installed for now. I'll
> definitely install it. Last time the installation ran without problems.
> CSSU. This is still a mystery for me. It's a sure choice then. I notice
> I am a bit noob :-D
>

> My Maemo and N900 knowledge is maybe abnormal (abnormally poor). I
> neearly sure not to have a properly configured device. Now it comes
> the special moment when I begin to study how to get my N900 properly
> configured :-)

Properly configured is something like what the device is like when taken
out of the retail box after buying it.. Maybe removing the location
widget and the calendar widget from the desktops.

Then after that there are lots of things you can install and do to make
it burn battery.

For example, if you turn off wifi power saving and connect to wifi, you'd
go down from several days of standby, to 6 hours of standby. Also if
your wifi access point doesn't support wifi powersaving, or has
broken/buggy wifi powersaving. (Which is probaly why one would turn it off
on N900) You said it happens also when not on wifi, so I guess that's the
problem in this case.

On 08/07/2012 04:20 AM, ext Cedric Cellier wrote:
> Of course offline mode is not normal. I suggested it
> for testing :) So that whatever software is the culprit
> it can no longer drain the battery very fast. If you can't
> stand several days in offline mode and without top reporting
> a process that's heavy on the cpu

It doesn't need to be that heavy.

Even a process that constantly wakes up just at 1s interval,
(which shows only as 0-1% of CPU usage in top) will
reduce device idle use-time from one week[1] to a day.

This is when just CPU is used. If also network is used,
the wakeups can be much rarer and they still ruin the use-time
even worse. I'm not completely sure of these numbers, but
if your WLAN accesspoint power management is working, I think
even <5 minute interval wakeups are bad, with phone networks,
the network access intervals need to be much longer for device
to be able to save power.

These kind of wakeup frequencies you don't notice with top, you
need either strace the programs or use e.g. nethogs[3] utility.

Note also that the weaker the network signal strength is,
the more power is required.

[1] A week with a full, *new* battery [2], no services installed etc.

[2] Battery capacity worsens with time, with use and higher temperatures
(check the manufacturing date when buying batteries!), see:
https://bugs.maemo.org/show_bug.cgi?id=7636#c16